The leader of Cardiff council has said she is “incredibly sad” her local high school had been placed in special measures.

Until June, Councillor Heather Joyce was chair of governors at Llanrumney High School, which this week received a damning inspection report by the education watchdog.

Estyn found “important shortcomings” in the majority of lessons and the school’s performance and prospects for improvement were deemed “unsatisfactory”.

Coun Joyce said: “We have got to look forward now. There are dedicated staff there, the governors are hard working and are dedicated.”

Llanrumney’s Labour ward councillor was reluctant to lay blame, saying “it would not do anyone good”, but said the school had suffered from a lack of investment.

“I am incredibly sad that it has come to this. It will go forward, I have got every confidence – let’s look forward,” she said.

Asked whether the board of governors were in part responsible, Coun Joyce again pointed to investment, saying: “The governors worked with what they had, as did the headteacher. You can only work with what you have got.”

The previous Liberal Democrat/Plaid Cymru administration last year abandoned plans to build a new school for east Cardiff on Rumney Rec following local opposition.

Councillor Keith Jones, one of the leaders of the campaign, said as well as a lack of investment from councils of all political persuasions, the school had suffered from a “huge amount of party politics”.

“Teachers are at the chalk-face doing the best they can to raise standards,” Coun Jones, a former Llanrumney High pupil himself, said.

“It was announced in 2006 that Llanrumney and Rumney (schools) was going to be closed. A whole generation has gone to the school knowing that the council wants to close it.

“It was very difficult, I think, and parents and teachers are to be commended for what they have done over the last few years.”

On Thursday night the Labour Cabinet approved plans to move all pupils at Llanrumney High to the Rumney High School site from September 2013.

The schools will remain as two distinct schools for the first 12 months. A council spokeswoman said all year groups would collaborate, but it had yet to be decided which specific classes would be taught together.

From September 2014, both will be closed and replaced with a new school – with a new name and possibly uniform – on the Rumney High site.

The plan is that all pupils will eventually be transferred to a newly built “state-of-the-art” school in September 2016, on a site to be decided after a consultation.

Coun Jones said it was important parents were told as soon as possible about what action was going to be taken following the Estyn report and about the practical implications of the new school, such as uniform and curriculum.